Tool and corresponding method for removal of material from within a body

ABSTRACT

A device for removing material from within the body, includes an elongated element formed from hollow segments sequentially interconnected at effective hinges. The device assumes an insertion configuration for insertion of the segments sequentially through an opening of a first dimension into the body. A portion of the elongated element inserted into the body progressively assumes a material removing configuration in which a relative position of each segment relative to an adjacent segment is delineated by the effective hinge together with additional abutment surfaces defining a fully deflected state of the effective hinge. The material removing configuration has at least two dimensions exceeding the first dimension. At least two of the segments are formed with at least one cutting configuration deployed so as to collect material into a hollow volume of the segment during progressive formation of the material removing configuration as the elongated element is advanced.

RELATED APPLICATIONS

This patent application is a National Stage of PCT/IB2009/053259 filedon Jul. 27, 2009, which claims the benefit under 119(e) of U.S.Provisional Patent Application No. 61/083,931 filed Jul. 27, 2008, thecontents of which are incorporated herein by reference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to devices and methods for removingmaterial from within a body, particularly where the volume of materialto be removed has at least two dimensions exceeding the lateraldimensions of the opening via which the volume is accessed. In certainpreferred embodiments, the invention provides a tool and method forremoving material from an intervertebral disc, such as in a discectomy.

Various techniques are known for performing minimal-invasive discectomy.Most commonly, conventional cutting and manipulation tools are usedunder endoscopic control to sever disc tissue and remove it through aworking channel. This approach is slow and tedious, particularly givenlimitations on the size of incision, and the risk of damage to the duralsac or nerve roots.

US Patent Application Publication No. 2007/0149990 to Palmer et al.proposes a tissue removal apparatus in which an elongated hollow deviceis formed from shape-memory materials that is biased to a predefinedcoiled form. The device has lateral cutting openings into which tissueis meant to be drawn under the influence of suction. The device is notsufficiently rigid to define a predictable path, and is described asloosening, tearing or disrupting tissue within the nucleus of the discduring insertion.

The unpredictability of the path that will be followed by the Palmerdevice during insertion may lead to a risk of perforation and injury.Additionally, the suction-based approach appears impractical foreffective removal of material along a long narrow device with openingsspaced along its length. Finally, the Palmer tool does not provide anydirect volumetric control of the quantity of material removed.

Turning now to PCT Patent Application Publication No. WO 2006/072941(hereafter “the '941 application”), this teaches a wide range of devicesand corresponding applications in which an elongated element isintroduced into a body in a straightened configuration and then assumesa curved or coiled configuration within the body. The '941 applicationis hereby incorporated by reference herein in its entirety. Unlessotherwise defined, terminology used herein is used in the same sense asdefined in the '941 application.

Certain embodiments described in the '941 application are implemented ashollow elements with an open tip and may perform limited tunneling orother removal of material from within a body. However, they are limitedin their capabilities for removal of material from a volume within abody having at least two dimensions exceeding the lateral dimensions ofthe opening via which the volume is accessed.

Of particular relevance as background to the present invention are theplanar spiral implementation of FIGS. 11-12C, and the three-dimensionalforms of FIGS. 10, 13 and 14, of the '941 application. As defined there,and as used herein, the term “spiral” is used in its colloquial sense torefer to any shape which spirals inwards/outwards, and is not limited toan exact geometric spiral which is referred to herein as a “perfectspiral”. The spiral formed from a stepped increase in radius ofcurvature as described here may be preferred due to its simplicity ofmanufacture. Nevertheless, it will be appreciated that it is possible tovary segment size and/or inter-segment spacing in a continuous manner toachieve a close approximation to a perfect spiral, or any other varyingcurvature profile desired.

There is therefore a need for a device for insertion into a body via anopening, and for removing material from within the body, which wouldfollow a predefined path and provide controllable volumetric removal ofmaterial from a target region within the body.

SUMMARY OF THE INVENTION

The present invention is a device for insertion into a body via anopening, and for removing material from within the body.

According to the teachings of the present invention there is provided, adevice for insertion into a body via an opening, and for removingmaterial from within the body, the device comprising an elongatedelement formed primarily from a plurality of hollow segmentssequentially interconnected so as to form an effective hinge betweenadjacent of the segments, the segments and the effective hinges beingconfigured such that: (a) the elongated element assumes an insertionconfiguration for insertion of the segments sequentially through anopening of a first dimension into the body; and (b) a portion of theelongated element inserted into the body progressively assumes amaterial removing configuration in which a relative position of eachsegment relative to an adjacent segment is delineated by the effectivehinge together with additional abutment surfaces defining a fullydeflected state of the effective hinge, the material removingconfiguration having at least two dimensions exceeding the firstdimension, wherein each of at least two of the segments is formed withat least one cutting configuration deployed so as to collect materialinto a hollow volume of the segment during progressive formation of thematerial removing configuration as the elongated element is advanced.

According to a further feature of the present invention, the elongatedelement is substantially straightened when in the insertionconfiguration.

According to a further feature of the present invention, the elongatedelement is resiliently biased to assume the material removingconfiguration.

According to a further feature of the present invention, the materialremoving configuration is configured such that, as the elongated elementis advanced, the material removing configuration progressively expandsin at least two dimensions.

According to a further feature of the present invention, the materialremoving configuration is configured to substantially close on itself soas to define a substantially contiguous contained volume.

According to a further feature of the present invention, at least partof the elongated element assumes a spiral configuration in the materialremoving configuration.

According to a further feature of the present invention, at least partof the elongated element assumes a helical configuration in the materialremoving configuration.

According to a further feature of the present invention, at least partof the elongated element assumes a conical shape in the materialremoving configuration.

According to a further feature of the present invention, the materialremoving configuration has three dimensions which all exceed the firstdimension.

According to a further feature of the present invention, each of thesegments has a substantially rectangular cross-section.

According to a further feature of the present invention, the at leastone cutting configuration comprises at least one louver.

According to a further feature of the present invention, the at leastone cutting configuration comprises at least two cutting configurationsdeployed on at least two sides of one of the segments.

According to a further feature of the present invention, the at leastone cutting configuration comprises at least three cuttingconfigurations deployed on at least three sides of one of the segments.

According to a further feature of the present invention, the elongatedelement includes at least five of the hollow segments.

There is also provided according to the teachings of the presentinvention, a method for removing material from a body, the methodcomprising: (a) providing a device comprising an elongated elementformed primarily from a plurality of hollow segments sequentiallyinterconnected so as to form an effective hinge between adjacent of thesegments, the segments and the effective hinges being configured suchthat: (i) the elongated element assumes an insertion configuration forinsertion of the segments sequentially through an opening of a firstdimension into the body; and (ii) a portion of the elongated elementinserted into the body progressively assumes a material removingconfiguration in which a relative position of each segment relative toan adjacent segment is delineated by the effective hinge together withadditional abutment surfaces defining a fully deflected state of theeffective hinge, the material removing configuration having at least twodimensions exceeding the first dimension, wherein each of at least twoof the segments is formed with at least one cutting configurationdeployed so as to collect material into a hollow volume of the segmentduring progressive formation of the material removing configuration asthe elongated element is advanced; (b) deploying the device in adelivery system; (c) forming an opening into the body; (d) advancing thedevice through the opening into the body such that the device assumesthe material removing configuration within the body; and (e) removingthe device through the opening together with material collected withinthe hollow volume.

According to a further feature of the present invention, the material isat least part of an intervertebral disc.

According to a further feature of the present invention, the material issoft tissue.

According to a further feature of the present invention, the material ishard tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1A is an isometric view of a device, constructed and operativeaccording to an embodiment of the present invention, for removingmaterial from within a body, the device being shown in a substantiallystraightened state prior to deployment;

FIG. 1B is an additional isometric view of a part of the device of FIG.1A;

FIG. 2 is a sequence of views, labeled (i) through (ix), illustratingthe progressive deployment of a material removal configuration accordingto embodiments of the present invention;

FIG. 3 is an enlarged view of the fully deployed state of the device ofFIG. 1A;

FIGS. 4A and 4B are isometric views of an embodiment of the inventionprior to and after deployment, respectively;

FIGS. 5A and 5B are isometric side views of the embodiment of FIGS. 4Aand 4B with a side cover of a delivery system removed, prior to andafter deployment, respectively;

FIGS. 6A and 6B are enlarged isometric views of a device from theembodiment of FIGS. 4A and 4B, shown prior to and after deployment,respectively;

FIGS. 7A and 7B are enlarged side views of the device of FIGS. 6A and6B;

FIGS. 8A and 8B are schematic representations of two stages in asurgical procedure according to an aspect of the teachings of thepresent invention employing the embodiment of FIGS. 4A and 4B;

FIGS. 9A and 9B are schematic isometric views of alternativeimplementations of a segment of the device of FIGS. 6A and 6B;

FIGS. 10A and 10B are schematic isometric views of an implementation ofa hinged interconnection between two segments, shown in a substantiallystraightened and a closed, deflected state, respectively, according to avariant implementation of the device of FIGS. 6A and 6B;

FIGS. 11A and 11B are schematic isometric views of a device, constructedand operative according to a further embodiment of the presentinvention, for removing material from within a body, the device beingshown in a substantially straightened state prior to deployment and acurved deployed state, respectively;

FIGS. 12A-12C illustrate schematically a sequence of devices accordingto FIG. 11B for use in a procedure according to a further aspect of thepresent invention; and

FIG. 13 is a schematic isometric view of a device, constructed andoperative according to a further embodiment of the present invention,for removing material from within a body, the device being shown in acurved deployed state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a device for insertion into a body via anopening, and for removing material from within the body, particularlywhere the volume of material to be removed has at least two dimensionsexceeding the lateral dimensions of the opening via which the volume isaccessed.

The principles and operation of devices and methods according to thepresent invention may be better understood with reference to thedrawings and the accompanying description.

By way of introduction, and introducing reference numerals which will beused generically to refer to similar features throughout the drawings,certain embodiments of the present invention provide a device forinsertion into a body via an opening, and for removing material fromwithin the body. By way of one non-limiting example, FIGS. 8A and 8Bshow an intervertebral disc body 100 with an opening 102. For simplicityof presentation, in most of the drawings, the body and opening areomitted. Generally speaking, the device of certain embodiments includesan elongated element, generally designated 10, formed primarily from aplurality of hollow segments 12 sequentially interconnected so as toform an effective hinge 14 between adjacent segments. Segments 12 andeffective hinges 14 are configured such that the elongated elementassumes an insertion configuration, typically substantiallystraightened, for insertion of segments 12 sequentially through anopening of a first dimension D₀ into body 100, for example, as seen inFIG. 8A. Segments 12 and effective hinges 14 are further configured suchthat a portion of the elongated element inserted into the bodyprogressively assumes a material removing configuration in which arelative position of each segment relative to an adjacent segment isdelineated by the effective hinge together with additional abutmentsurfaces defining a fully deflected state of the effective hinge, forexample, as shown in FIG. 8B. The material removing configurationpreferably has at least two dimensions D₁ and D₂ exceeding firstdimension D₀. It is a particular feature of an embodiment of the presentinvention that two or more of segments 12 are each formed with at leastone cutting configuration 16 deployed so as to collect material into ahollow volume 18 of the segment during progressive formation of thematerial removing configuration as the elongated element is advanced.

The progressive deployment of various embodiments is best illustratedwith reference to an embodiment of the invention illustrated in FIGS.1A-3. Specifically, FIGS. 1A and 1B show an embodiment of a device,constructed and operative according to the teachings of the presentinvention, with elongated element 10 formed from a sequence of segments12 interconnected at effective hinges 14 and exhibiting cuttingconfigurations 16 deployed to collect material into a hollow volume 18.This embodiment may be regarded as an expanding cutter or “grater”formed from a spirally expanding element based on the principles ofFIGS. 11-12C of the aforementioned '941 application. The cuttingconfiguration may be any form of tooth, scoop or other cutting elementconfigured and suitable implemented for collecting or cutting theparticular material to be removed. In the preferred but non-limitingimplementation illustrated here, cutting configuration 16 is a singlewide scoop-like tooth. In the case of a metallic structure, this toothmay optionally be stamped out or otherwise formed in the metallicmaterial from which the device is formed, resembling the “teeth” of adomestic grater. This structure is believed to be particularly suitablefor removal of some, or substantially all, degenerated intervertebraldisc material, in some cases in preparation for insertion of anintervertebral implant or graft, the size of which corresponds to thevolume of disc removed.

In the exemplary embodiment shown here (FIGS. 1A-3), the grater is ahollow square tube which is incompletely cut at certain intervals,typically by removal of V-shaped slots of varying widths, rendering thetube as a series of links connected by integral joints. The anglesbetween the links, defined by the width of the slots, are predesigned toallow curling of the structure in the same plane as the grater ispropelled out of the delivering conduit. However, many other metals,alloys and non-metallic materials are also considered suitable.

Operation of the device, corresponding to a method according to thepresent invention, may be understood by reference to the stages ofdeployment shown in FIG. 2. The device is brought to the desiredlocation and is advanced beyond the end of a delivery conduit 20. Thedevice curls on itself in gradually enlarging diameters, expanding intwo dimensions and at the same time cutting/grating away the surroundingtissue (or other material) which is collected within the internal volumeof the device. After the desired volume has been cut, the device isgradually withdrawn back into the conduit, and the conduit removed,taking with it the contained cut material. The hollow volume is thenavailable for introduction of implants, etc.

The device of embodiments of the present invention is particularlyapplicable for deep tissue sampling, for removal of deep seated tissues(intervertebral discs, tumours etc.), and for creating voids or spacesto allow deployment of implants, introduction of bone cement, drugdelivery, etc. in those spaces. The same underlying principles may beused to implement a device for industrial and other non-medicalapplications, for example, to create deep seated anchorage, obtainedthrough small apertures.

The shape, size and positioning of the cutting configuration may bevaried as needed. For example, in certain applications, the tooth may bewider, or a number of separate teeth may be deployed, to cut surroundingmaterial from a width at least equal to the width of the body ofsegments of the instrument, thereby facilitating the radial expansion ofthe instrument even in relatively rigid material.

Optionally, the rearward-facing edge of the opening facing the cuttingconfiguration may be implemented with a sharp edge and the internallumen of the segments and/or the cutting configuration may beimplemented with projecting retention features (not shown) to inhibitloss of the cut material during withdrawal of the cutting instrument.These retention features may include, but are not limited to,rearward-facing pins or barbs.

As mentioned earlier, the geometrical form of the cutting instrument inits deployed state need not be a perfect spiral, and may instead havegroups of slots with the same width, or any other desired sequence ofslot widths which define a gradually increasing diameter structureeffective to achieve the desired expanding form.

Most preferably, a biasing arrangement is provided to bias the cuttinginstrument to its spirally curved deployed state as it emerges from thedelivery conduit. This may simply be implemented as a tensioned elementpassing along the inside of the tool on the side facing inwards towardsthe center of the spiral. The element may be tensioned by a springand/or an arrangement of gears, or by any other tensioning arrangement.Alternatively, shape memory properties may be employed to providebiasing to the deployed state. Examples of various biasing arrangementswill be discussed further below. Additionally, or alternatively, anintersegment locking mechanism such as described in PCT PatentApplication Publication No. WO 2008/084479 may be provided.

Turning now to an embodiment of the present invention illustrated withreference to FIGS. 4A-8B, this embodiment is generally similar to theembodiment of FIGS. 1A-3, also relating to a device which assumes asubstantially spiral material-removing configuration. Throughout thisdocument, except where explicitly contrasted, or where clearlyincompatible, the various features of structure and operation of thevarious embodiments presented herein should be understood to beinterchangeable between the embodiments. Thus, for example, theprogressive deployment illustrated above with reference to FIG. 2 isequally applicable to all of the embodiments presented herein, while thedelivery system and applications which will be described with referenceto FIGS. 4A-8B are also equally applicable to all of the embodimentspresented herein.

Referring specifically to FIGS. 4A-5B, these show an example of adelivery system for operating embodiments of the present invention.FIGS. 4A and 5A show conduit 20 with elongated element 10 withdrawninside it in a substantially straightened state, either prior todeployment or after withdrawal, while FIGS. 4B and 5B show elongatedelement 10 in its fully deployed material-removing configuration. Theexample illustrated here is configured for manual operation, by rotatingknob 22 which includes a gear wheel engaged on a gear tooth rack (notshown), thereby providing controllable and precise motion of the devicealong conduit 20. Clearly, alternative manual actuators, and variouselectrical or otherwise powered actuators, may readily be implemented byone ordinarily skilled in the art.

It will be noted that embodiments of the present invention providevolumetric material removal. Specifically, since the path followed byelongated element 10 during deployment is well defined, and the volumeswept through by elongated element 10 at any stage of deployment isknown, it is possible to define with considerable accuracy what volumeof material will be removed by advancing the device to various definedpositions. Thus, in an embodiment of the present invention, the deliverysystem provides graduated markings, or otherwise indicates quantitativeinformation associated with the actuation mechanism, to allow anoperator to remove a controlled and defined quantity of material fromwithin the body.

As best seen in FIGS. 5A and 5B, this implementation of the deliverysystem also includes a biasing spring 24 deployed to maintain theaforementioned bias of elongated element 10 towards its closedmaterial-removing configuration by applying tension to a tensioningelement or “draw-cord” (not shown) deployed along the elongated element.It will be understood that, during successive deployment of elongatedelement 10, relative motion occurs between the elongated element and thedraw-cord. The resulting slack can either be taken up elastically by thespring, or can be compensated by implementing a differential geararrangement which causes different rates of movement of the elongatedelement and the anchor of the spring. In alternative embodiments wherethe hinged interconnection or other local inter-segment elements providethis bias, biasing spring 24 may be omitted.

The biasing arrangement is preferably configured to provide relativelystrong biasing such that, under normal operating conditions, elongatedelement 10 at all stages assumes a well defined and substantially rigidform in which any portion of the element still within conduit 20 ismaintained in its straightened state and any part already extendingbeyond the end of conduit 20 assumes its fully-deflected curved (e.g.,spiral) state. As a result, elongated element 10 follows a well definedand predictable path as it advances into the body, thereby minimizingrisks of damage such as may be caused by various types of flexible toolswhich may inadvertently stray from their planned paths. The rigidity ofthe device is further enhanced in certain embodiments where loops of theresulting structure close against each other in direct contact.

The deployment device also includes a support shaft 26 which may beclamped in a given position so as to support conduit 20 in a desiredposition and orientation. Optionally, an endoscope (not shown) can beincorporated with conduit 20 to facilitate inspection of the results ofthe material removal. Alternatively, after completion of amaterial-removal procedure, the device can be withdrawn from at leastpart of conduit 20 to allow insertion of a stand-alone endoscope alongthe conduit lumen for the same purpose.

Although illustrated here with a straight conduit 20, it will be clearthat conduit 20 may be implemented with various degrees of curvaturewithout adversely affecting operation of the invention, and in certaincases, to advantage. Even in cases where conduit 20 exhibits significantcurvature, the state of elongated element 10 within the conduit isreferred to as “substantially straightened”, in clear contrast to thecurved deployed state which the element assumes on leaving the conduit.

FIGS. 6A-7B show an embodiment of elongated element 10 in more detail,with FIGS. 6A and 7A showing the substantially straightenedconfiguration and FIGS. 6B and 7B showing the fully deployedmaterial-removing configuration. This embodiment differs from that ofFIGS. 1A-3 in that it employs dedicated hinge structures to defineeffective hinges 14 with precise hinge axes between segments. Thisembodiment also employs individually varying segment shapes in order tosubstantially close on itself so as to define a substantially contiguouscontained volume. In this context, “substantially contiguous” is used torefer to a deployed material-removing configuration in which spacesbetween successive turns of the structure are minimized. As a result,the device is typically effective to remove a block of material to leavea roughly unitary cavity within the body.

In the particular preferred embodiment illustrated here, the form of thesegments and the position of the hinges is configured to achieve a closeapproximation to an Archimedean spiral. This form has the addedadvantages of employing segments of roughly uniform heights (radialsteps in the spiral) and maintaining a roughly linear relation betweenthe length of the elongated element deployed and the volume of materialremoved.

This embodiment is illustrated here with 11 hinged segments 12. Thenumber of segments can clearly be varied according to the intendedapplication, primarily as a function of the ratio of the volume to beremoved and the dimensions of the opening through which access isachieved. Typically, elongated element 10 includes a minimum of fivehinged segments 12, and preferably at least 10 hinged segments.Preferably, no more than 30 segments are used.

The cutting configurations 16 in this embodiment are implemented asslats or “louvers” which extend across the full width of segments 12.Depending on the type of material to be removed and the designconsiderations of the device, these louvers may be either unsharpenedwall portions or they may feature a sharpened cutting edge, with orwithout serrations or other cutting enhancing features. The cuttingedges and/or entire cutting configurations may be implemented from thesame materials used for the rest of segments 12 or may be implementedfrom different materials or with specific coatings to impart specificmechanical or physiological properties. For example, in certainnon-limiting implementations, part or all of the cutting configurationsare coated in a low-friction material, such as PTFE, so as to facilitatepassage of material into contained volume 18. The inner lumen of thedevice may have a relatively higher friction surface which helps to gripthe contained material while the device is removed.

It should be noted that the term “cutting configuration” is used hereinto refer to any cutting configuration which enables a segment 12 otherthan the leading segment of elongated element 10 to cut material incontact with which it is moving. In this sense, they may be referred toas “lateral cutting configurations.” In the case of the spiral expansionillustrated here, the primary cutting direction is in the radiallyoutward direction as shown here.

Referring parenthetically to FIGS. 9A and 9B, embodiments of the presentinvention are not limited to cutting in a single lateral direction. FIG.9A illustrates an example in which some or all of segments 12 areimplemented as shown with two cutting configurations 16 and 16′ deployedon two sides of the segments. FIG. 9B illustrates an example in whichsome or all of segments 12 are implemented as shown with three cuttingconfigurations 16, 16′ and 16″ deployed on three sides of the segment.These embodiments may be used to advantage in cases where the elongatedelement expands in three dimensions during deployment in thematerial-removing configuration, or even in a planar (e.g., spiral)embodiment where the device expands between inwardly pressing layers oftissue.

Referring again to FIG. 6A, the embodiment illustrated here employssegments which have alternating larger and smaller widths (i.e., thedimension parallel to the effective hinges). Optionally, this allows theedges of adjacent segments to be implemented with slight overlap in thedeployed state. In certain preferred embodiments, the overlapping edgesare configured to come together with a scissors cutting action which mayprovide an additional cutting effect. This effect may be particularlyhelpful where significant mechanical forces are encountered resistingadvancing of the device, sometimes acting against the aforementionedbiasing arrangements to cause momentary opening of gaps between thesegments. The scissors cutting action is then effective to facilitatere-closure of the structure, and provides and added cutting effect.

Turning now to FIGS. 8A and 8B, an application of an embodiment of theinvention for intervertebral discectomy is illustrated. The device isdeployed with elongated element 10 within delivery conduit 20 of thedelivery system (not shown), and the delivery conduit 20 is insertedthrough an opening 102 in the body 100 (FIG. 8A). The device is thenadvanced via conduit 20 through opening 102 into body 100 such that itassumes the material removing configuration within the body (FIG. 8B).The device is then removed via conduit 20 through opening 102 togetherwith the material collected within the hollow volume.

As mentioned above, at least two dimensions D₁ and D₂ of the materialremoving configuration are preferably greater than the dimension D₀ ofopening 102. In this context, the dimension D₀ may be taken as thelargest dimension to which the minimally invasive incision is opened.For the purposes of evaluating a device according to the presentinvention, for practical purposes, dimension D₀ may be taken to be themaximum transverse dimension of the part of conduit 20 which is insertedinto the body.

The procedure described with reference to FIGS. 8A and 8B may beemployed as a step in a wide range of surgical procedures. In a simpleexample, the process may be a self-contained process for removal oftissue, for example, for reduction of intra-discal pressure to alleviatea herniated disc and/or for a biopsy. In the case of a biopsy, acomplementary tool, typically in the form of a rectangular rod, may beprovided for insertion along elongated element 10 after use, typicallyfrom the distal tip in a proximal direction, to expel the sampledmaterial from contained volume 18 when required.

Alternatively, removal of material from an intervertebral disc may beperformed to clear space for introduction of a spacer or othermobility-preserving implant, or for delivery of various drugs,brachytherapy seeds or other materials or tools.

In cases of vertebral fusion, the procedure may be performed once ormore until bleeding bone is exposed for the two facing vertebralsurfaces, followed by introduction of a cage and/or introduction offiller material, cement, bone, bone graft material, bone morphogeneticproteins, osteogenetic material etc., for promoting fusion of theadjacent vertebral bodies.

Where a device or other materials are to be delivered to the intra-bodysite, this may advantageously be performed after removal of elongatedelement 10 via the same conduit 20 used for insertion of the device. Incertain implementations of the invention, such devices or materials maybe introduced along the lumen of another subsequently inserted elongatedelement 10 inserted after initial removal of material from within thebody.

It will be clear that embodiments of the present invention allow removalof significant quantities of material from within a body in anefficient, reliable and predictable manner via a small incision. Forexample, continuing with the example of removal of material from anintervertebral disc, an exemplary device for insertion via an opening oftransverse dimensions no more than 4.5 mm by 4.5 mm is preferablyconfigured to remove a quantity in excess of 1 cc, and most preferablyat least 2 cc. For this purpose, a device of length (when straightened)of at least about 15 cm, and preferably at least about 20 cm, is used.

Although illustrated here in a particularly preferred exemplaryapplication of surgery involving an intravertebral disc, it should beappreciated that the invention is not limited to such applications, andmay readily be used in a range of other applications. Additionalnon-limiting examples include procedures for performing biopsy of bonetissue, for example, in vertebral bodies or in a femur.

Turning now to FIGS. 10A and 10B, these drawings illustrate analternative form of effective hinge attachment between adjacent segments12, which may be implemented to particular advantage using shape-memorymaterials. In certain cases, an integral hinge may not provide arequired level of precision as to the position of the axis of rotation.On the other hand, assembly of separate hinge structures may presentmanufacturing challenges, and typically does not allow for incorporatingresilient biasing into the hinge structure itself. This embodimentpresents an alternative form of effective hinge which can bemanufactured as part of the segment structure but which also providesprecise location of the hinge axis of rotation.

Specifically, the implementation shown here employs a torsion bar 28 todefine the axis of rotation. The ends of torsion bar 28 are anchored toone segment while the middle of the bar is anchored to the adjacentsegment. This allows effective hinge motion between the two segmentsbetween an open/straightened position as in FIG. 10A and a closedposition as in FIG. 10B for forming the material-removing configuration.

In certain cases, the structure shown may advantageously be formed froma shape-memory material, such as Nitinol, preformed to return to theclosed state of FIG. 10B. In this way, the hinge structure itselfprovides the aforementioned resilient bias for the device to assume itsmaterial-removing configuration.

Turning now to FIGS. 11A-12C, in contrast to the spiral configurationsillustrated above, these drawings illustrate an embodiment of theinvention in which elongated element 10 assumes a generally helicalmaterial-removing configuration. As described in the '941 application,deployment of the effective hinge axis at a slightly oblique anglegenerates a helical progression of the element in its closed state. Heretoo, this progression can be used to advantage with addition of lateralcutting configurations to achieve effective removal of material. Thisapproach facilitates removal of a volume of material with threedimensions which all exceed the dimension of the opening through whichthe device is inserted. This is particularly advantageous in allowingdelivery of a device of given dimensions via a minimally invasiveincision of dimensions significantly smaller than would be required byother techniques, with resulting improvements in safety of the procedureand reduction in recovery times.

A helical implementation typically performs much of the material cuttingwith the open end of the leading segment, while the outward projectinglateral cutting configurations further contribute to increasing thediameter of the hollowed volume and smoothing or scraping the surfaces.Additionally, or alternatively, axially projecting lateral cuttingconfigurations (not shown) may be deployed on the top loop of the helixin order to enhance the axial (height) progression of the device.

Embodiments such as the helical embodiment in which the leading segmentremains in a leading position open up additional options of using theinner lumen of the device, prior to, during and/or after insertion as apassageway for deployment of additional tools and/or materials.According to one non-limiting example, an oversize drill bit or otherdevice for breaking-up the material ahead of the device can be driven bya flexible drive shaft passing along the lumen, thereby facilitatingadvance of the device through the material.

In some cases, a helical removal structure leaves a central core ofuncut material. If necessary, the central core which lies within thehelical structure may be removed by conventional techniques afterelongated element 10 has been withdrawn. Alternatively, as illustratedschematically in FIGS. 12A-12C, effective complete removal of anydesired volume of material may be achieved by using a sequence ofhelical elements designed to form material-removing configurations of asequence of different diameters.

Finally, referring briefly to FIG. 13, it should be noted that thematerial-removing configurations of the present invention are notlimited to spiral and helical configurations. For example, asillustrated in FIG. 13, elongated element 10 may be configured toprogressively assume a conical deployed form as shown. This form allowscutting expansion in both radial and axial directions simultaneously.

It will be appreciated that the above descriptions are intended only toserve as examples, and that many other embodiments are possible withinthe scope of the present invention as defined in the appended claims.

1. A device for insertion into a body via an opening, and for removingmaterial from within the body, the device comprising: an elongatedelement formed primarily from a plurality of hollow segmentssequentially interconnected so as to form an effective hinge betweenadjacent of the segments, the segments and the effective hinges beingconfigured such that: (a) the elongated element assumes an insertionconfiguration for insertion of the segments sequentially through anopening of a first dimension into the body; and (b) a portion of theelongated element inserted into the body progressively assumes amaterial removing configuration in which a relative position of eachsegment relative to an adjacent segment is delineated by the effectivehinge together with abutment surfaces of sequentially adjacent segmentsin contact with each other, thereby defining a fully deflected state ofthe effective hinge, said material removing configuration having atleast two dimensions exceeding said first dimension, wherein each of atleast two of the segments is formed with at least one cuttingconfiguration deployed so as to collect material into a hollow volume ofthe segments during progressive formation of said material removingconfiguration as the elongated element is advanced.
 2. The device ofclaim 1, wherein the elongated element is substantially straightenedwhen in said insertion configuration.
 3. The device of claim 1, whereinthe elongated element is resiliently biased to assume said materialremoving configuration.
 4. The device of claim 1, wherein said materialremoving configuration is configured such that, as the elongated elementis advanced, said material removing configuration progressively expandsin at least two dimensions.
 5. The device of claim 1, wherein saidmaterial removing configuration is configured to substantially close onitself so as to define a substantially contiguous contained volume. 6.The device of claim 1, wherein at least part of the elongated elementassumes a spiral configuration in said material removing configuration.7. The device of claim 1, wherein at least part of the elongated elementassumes a helical configuration in said material removing configuration.8. The device of claim 1, wherein at least part of the elongated elementassumes a conical shape in said material removing configuration.
 9. Thedevice of claim 1, wherein said material removing configuration hasthree dimensions which all exceed said first dimension.
 10. The deviceof claim 1, wherein each of said segments has a substantiallyrectangular cross-section.
 11. The device of claim 1, wherein said atleast one cutting configuration comprises at least one louver.
 12. Thedevice of claim 1, wherein said at least one cutting configurationcomprises at least two cutting configurations deployed on at least twosides of one of said segments.
 13. The device of claim 1, wherein saidat least one cutting configuration comprises at least three cuttingconfigurations deployed on at least three sides of one of said segments.14. The device of claim 1, wherein said elongated element includes atleast five of said hollow segments.
 15. The device of claim 1, whereinsaid effective hinges between adjacent of the segments are implementedas integral hinges.
 16. The device of claim 1, wherein said effectivehinges between adjacent of the segments are implemented as hingestructures connecting separately formed segments.
 17. The device ofclaim 1, wherein said effective hinges between adjacent of the segmentsare implemented as shape-memory hinges.
 18. A method for removingmaterial from a body, the method comprising: (a) providing a devicecomprising an elongated element formed primarily from a plurality ofhollow segments sequentially interconnected so as to form an effectivehinge between adjacent of the segments, the segments and the effectivehinges being configured such that: (i) the elongated element assumes aninsertion configuration for insertion of the segments sequentiallythrough an opening of a first dimension into the body; and (ii) aportion of the elongated element inserted into the body progressivelyassumes a material removing configuration in which a relative positionof each segment relative to an adjacent segment is delineated by theeffective hinge together with abutment surfaces of sequentially adjacentsegments in contact with each other, thereby defining a fully deflectedstate of the effective hinge, said material removing configurationhaving at least two dimensions exceeding said first dimension, whereineach of at least two of the segments is formed with at least one cuttingconfiguration deployed so as to collect material into a hollow volume ofthe segments during progressive formation of said material removingconfiguration as the elongated element is advanced; (b) deploying thedevice in a delivery system; (c) forming an opening into the body; (d)advancing the device through the opening into the body such that thedevice assumes the material removing configuration within the body; and(e) removing the device through the opening together with materialcollected within said hollow volume.
 19. The method of claim 14, whereinsaid material is at least part of an intervertebral disc.
 20. The methodof claim 14, wherein said material is soft tissue.
 21. The method ofclaim 14, wherein said material is hard tissue.